1. Field of the Invention
The present invention relates to a medical prosthesis stopping gastric content from refluxing into the esophagus, including a tube made in a biocompatible polymer material resistant to gastric acid. One end is attached above the stomach and the other one is left free in the stomach.
2. Discussion of the Related Art
This type of prosthesis, described in WO91 01117, describes the shape of a valve with an opening passage kept closed elastically. The section of the passage is progressively narrowed to a permanent shape so as to close the lower end of the tube so that in a position of maximum opening, the section is approximately as wide as the upper end attached to the lower end of the esophagus. This is a description of a valve that is opened by a force capable of overcoming the elastic forces that tend to keep it closed. Such a concept implies a relatively rigid prosthesis that will allow its closure in the absence of any force capable of opening it, this force being generated by the peristaltic pressure exerted on the food bolus by the esophagus.
This solution is unsatisfactory as it creates a situation that is contrary to what naturally occurs, so that the peristaltic pressure has to open the valve.
In certain cases, for example when food is swallowed that has not been sufficiently chewed, an increased force is necessary to allow passage of the food bolus through the esophagus and if a further force is necessary to open the valve, there is either a risk of blocking food or of causing pain or both.